Journal of Research of the National Bureau of Standards
AbstractAn integral equation for the distribution of current along a cylindrical antenna in a conducting dielectric is derived. It is shown that the boundary conditions for an antenna in such a medium are formally the same as for an antenna in free space. The equation is solved for the current I and the driving-point impedance Z by means of a technique that achieves sufficiently high accuracy in the leading terms of an iteration procedure so that the higher-order terms do not need to be evaluated. Moreover, these leading terms consist only of trigonometric functions with complex coefficients. The electromagnetic field in the infinite dissipative medium may be computed relatively easily since the current in the antenna is expressed in such simple terms. A numerical analysis is made to determine the properties of an antenna with an electrical length of one-half wavelength in the medium with conductivity s and relative dielectric constant er. Universal curves are given of I/v(er) with s/(?e0er), as the parameter and of Zver with s/(?e0er) as the variable in the range 0 < s/(?e0er) < 0.4. A table of numerical values of the impedance is given for media such as an isotropic ionosphere, dry salt, dry earth, wet earth, and lake water.
CiteJournal of Research of the National Bureau of Standards. Section D: Radio Propagation, Vol. 64D, No. 4, p. 365
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